The present disclosure relates generally to a valve opening control apparatus and method of controlling a gasoline exhaust gas recirculation (EGR) system and, more particularly, to a valve opening control apparatus and method of controlling a gasoline EGR system in which a flow rate of an exhaust gas to be flow in an intake line is controlled by controlling an opening amount of an EGR valve according to a clogging state of an emergency (EM) filter fluidly connected to a recirculation line located at a rear end of a turbocharger, in a gasoline engine vehicle including the gasoline EGR system.